This invention is in the field of optical elements such as lenses for X-ray and other penetrating radiations, including gamma rays. Until this invention, the primary manner by which such radiations have been focused is by using so-called "grazing" optics. These optics are plane or curved surfaces from which the radiations reflect for a very shallow angle of incidence. Although Bragg angle reflectors for X-rays and other penetrating radiations are known, their uses have been mainly in X-spectrometers and X-ray lasers. In the case of spectrometers, the reflectors are used to direct incoming radiation onto a detector; in lasers; the reflectors are used to define the resonate cavity of the laser. None of the known x-ray optics are capable of changing focus, which the instant invention can do.